{"title":"Competition between Disentanglement Effect and Interfacial Effect Determines the Chain Relaxation Dynamics of Entangled Ultrathin Polystyrene Films","authors":"Fengliang Wang, Sijia Li, Hongkai Guo, Jiaxiang Li, Jianquan Xu, Tongfei Shi, Xinping Wang","doi":"10.1021/acs.macromol.4c01788","DOIUrl":null,"url":null,"abstract":"Polymer–substrate interfaces can alter the dynamics of a confined polymer film. However, the influence of interfacial interactions on chain dynamics is unclear owing to difficulty in measurement. Herein, the effects of substrate–polymer interactions on the chain relaxation dynamics of confined-entangled polystyrene (PS) thin films were investigated. The chain relaxation time of a PS film on substrates with interfacial energies (γ<sub>s–p</sub>) of 44.9 and 2.3 mJ m<sup>–2</sup> monotonically decreased and increased, respectively, with a decrease in film thickness. The chain relaxation time of the PS film on substrates with γ<sub>s–p</sub> ranging from 33.5 to 10.6 mJ m<sup>–2</sup> decreased and then increased with decreasing film thickness, and this trend become monotonically increasing with the decrease of γ<sub>s–p</sub>. A new model describing this particular relaxation behavior is proposed and was used to elucidate the origin of the nonmonotonic chain relaxation dynamics of PS chains, which is attributed to the competition between disentanglement and substrate effects. The former accelerates while the latter retards the chain relaxation dynamics of the PS films. The impact of the PS free surface on relaxation dynamics decreases rapidly with the decrease of γ<sub>s–p</sub>. This phenomenon was further confirmed via Monte Carlo simulations. These results provide a new perspective for elucidating the mechanism of interface interactions affecting chain relaxation in the confined polymer film.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.1000,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Macromolecules","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.macromol.4c01788","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
Polymer–substrate interfaces can alter the dynamics of a confined polymer film. However, the influence of interfacial interactions on chain dynamics is unclear owing to difficulty in measurement. Herein, the effects of substrate–polymer interactions on the chain relaxation dynamics of confined-entangled polystyrene (PS) thin films were investigated. The chain relaxation time of a PS film on substrates with interfacial energies (γs–p) of 44.9 and 2.3 mJ m–2 monotonically decreased and increased, respectively, with a decrease in film thickness. The chain relaxation time of the PS film on substrates with γs–p ranging from 33.5 to 10.6 mJ m–2 decreased and then increased with decreasing film thickness, and this trend become monotonically increasing with the decrease of γs–p. A new model describing this particular relaxation behavior is proposed and was used to elucidate the origin of the nonmonotonic chain relaxation dynamics of PS chains, which is attributed to the competition between disentanglement and substrate effects. The former accelerates while the latter retards the chain relaxation dynamics of the PS films. The impact of the PS free surface on relaxation dynamics decreases rapidly with the decrease of γs–p. This phenomenon was further confirmed via Monte Carlo simulations. These results provide a new perspective for elucidating the mechanism of interface interactions affecting chain relaxation in the confined polymer film.
期刊介绍:
Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.